Transformer cut-out for alternating-current circuits.



CURRENT GIRQUTS.

PPLIGILTO l-LBD JULY 15, `1909.

T FOR LLTERN UNITED STATES PATENT o JOHN SEDG'WIICKy PECX, 0F TRAFFORDIARK, MANCHESTER, ENGLAND, ASSIGNOR TO WESTINGHOUSE ELECTRIC ANDMANUFACTURING COMPANY, A GORPORATION OF PENNSYLVANIA.

TRANSFORMER CUT-OUT lFOB. ALTERNATING-QURRENT CIRCUITS.

, Patented Ang. 27,1912. serial No. 5o7,7 5o.

Avlowing is a speciication.

My invention relates to alternating cur` rent electric distributionsystems and particularly to systems in which main and auX- iliarytransformers are employed.

windings,

vmain transformer to It has heretofore been proposed to provide anautomatic switching device to be operated through a relayby variationsinthe current supplied to, or delivered byl the transformers, for shortcircuiting the auxiliary transformer primary and secondary or foropening and closing the primaryv and secondary windings .of the maintransformer when a parallel system is utilized.

One object of the present invention is to provide improved devices inconnection with tlie relay switch which tion of the automatic switch,another object of the invention being to provide `an improved devicewhereby the blowing of a. fuse in the auxiliary transformer circuit whenthe main transformer is not in use shall cause the automatic 'switch toclose and therebytransfer the load to the main trans former in order toavoid interruption in the supply of energy.

In systems where main Aand auxiliary transformers are so arranged thattheir secondary windings are connectedin' parallel to. `Supply hashitherto been considered necessary' to install two switches in thesecondary circuit, one switch beingin the neutralI wire'wliich isconnected to the middle point of themaiii transformer secondary winding,and the other being in the circuit of one outer con-` ductor-which-isconnected toone end vof the said secondary winding, or a switch isemployed in each outerfconductor.

A. further object of the present invention is to provide an improvedarrangement for opening and closing the connections of the the circuit,in a system of the above mentioned chafa ter, ingwhich only a singleswitch is Arequir ed..

In the accompanying drawings, Figures 1,

when a series system is employed,

governs the operaf energy to a three-wire circuit, it`

cuit.

3 and 4 are diagrammatic views of distribution systems embodying myinvention. Referring now to Fig. 1, which illust-rates a distributionsystem having main and auX-` iliary transformers connected in serieswith one another, a main transformer being indicated at 1 as .having aprimary winding 3 and a secondary winding 4, and an auxiliarytransformer beingsiiidicated at 2 as having a primary winding`5 and asecondary winding 6. .The primary windings 3 and 5 are connectedin-series with each other between fthe conductors 7 8 of the supplycircuit,

and the secondary windings 4 and 6 are similarly connected. The primarywinding 5 of the auxiliary,l transformer 2 is arranged to be shortcircu-ited by means of a switch when the loatl on the system becomesconsiderable, and the secondary winding 6 of the transformer 2 isarranged to be similarly short circuited by meaiis of a switch 14comprising lixed contact terminals 12 and 13 which are connected,respectively, to the v junction 11 of Ythe windings 4 and 6 and to aconductor :10 of the distributing circuit 9410. The 'movable bridgepieces 45 and 1G ofthe respective switches 14 and 15 are arranged to beoperated by means of an electro-1nagnctically actuated member 17 whichis provided with a closing coil. 18 and an opening coil 19. One terminalof the closing coil 1S is connected to the contact terminal 13 of theswitch 14 and one terminal of the opening coil 19 is connected to oneofy the stationary contact terminals 20 of a switch A 21, the otherstationary contact terminal. 22 of whic is connected through indicatinglamps 23 to the conductor 9 of the distributing circuit. The otherterminals of the Aopening' coil 19 and the closing coil 18 areconnected, respectively, tothe contact termi# nals 24 and 25 of a relayswitch 26 having a contact arm 27 which is electrically connected to theconductor 9 and isl arranged to be moved against the'action cfa spring28 by means of an electro-magnet 29 in order to effect engagement withthe contact tere minal 24. IThe coil of the electro-magnet 29 may besupplied with current from the secondary winding 30 of a seriestransformer 31, the primary winding 32 of which is connected in theconductor 8 of t-he supply cir A contact.l terminal 33 of the switch 15is connected to an intermediate point in ico the winding -32 of theseries transformer 31,

so that, when the switch 15'is closed, a portion of the turns of thewinding 32 are short circuited to reduce the voltage impressed upon thecoil of the electro-magnet 29 of the relay switch 26. l

The movable contact member 34 of the switch 21 is pivoted at 35 and isnormally V held in engagement with'the contact terminal 20, against theact-ion of a weight 36, 'by means of a bell crank lever 37, one arm 38of which engages a projection 39 on said contact member and the otherarm '40 of which is connected to a fuse 41 'which is included in circuitwith the conductor 10 of the distributing circuit. The member 17 novidedwith a projection 42 to be engaged by contact member 34 to move theswitc es 14 and 15 into their closed positions.

The operation of the apparatus is as follows: 1When the load upon thesystem is light, the various' switches occupy the posi# tionsillustrated in Fig. 1 and the mainand auxiliary transformers areconnected in series with each other across the supply and distributioncircuits. tlf, however, the load increases to a predetermined value,the'current traversing the series transformer 31 bccomes sufficient toso energize the electrovau magnetv 29 that it will move the member 27'of the relay switch26 into engagement with the cont-actterminal 24. Acircuit is thereby completed through the closing coil 18 of the switches14 and 15 whereby said switches are closed and the auxiliary transformerto the coil by over-heating is greatly re duced. If the load on thesupply circuit be reduced below the predetermined value at which theelectro-magnet 29 is adjusted to operate. the member 27 of the relayswitch 26 will be moved by the spring 28 into engagement with thecontact terminal 25 and a circuit will thereby be completed through theopening coil 19 to openthe switches 14 and 1.5. It', at any time duringthe opera tion under light load conditions, the current traversing thewinding 6 of the auxiliary transformer 2 increases to such proportionsas to blow the fuse 41, the bell crank lever 37 will release contactmember 34 of the switchv21, and this contactmember willbe moved by theweight 36 to close the'switches 14 and 15 and also to break the circuit.able bridge piece 45 of the through the opening'coil 19 and complete acircuit through the indicating lamps 23. The attention of the attendant:will thus be drawn to the fact that the auxiliary transformer circuithas been interrupted, and, since it will be impossible to complete acircuit through the opening coil 19, the switches 14 and 15 will remainclosed.

Referring now to Fig. 2, a modification is illust-rated as applied to asystem in which the main and auxiliary transformers 1 and 2 'areconnected in parallel with each other, the switches 14 and 15 beinarranged. to

open and close the circuits of t e main transformer windings. Theoperation of the apparatusis similar to that of the apparatus .shown inFig. 1 `-and need not be further described.

Referring now to Fig. 3, the invent-ion is illustrated as applied to athree-wire system in which .the circuit connections of the main andauxiliary transformer 1EL and 2a are arranged to be effected bymeans'of, a single switch, in the manner set forth inu my application,Serial No. 489,253, tiled April 12, 1909, the arrangement of the meansfor controlling the closing and opening coils of the switches 14 and 15and for preventing these switches from being opened when a fuse 41 inthe secondary circuit of the main transformer has been destroyed, beingsimilar to those already described with reference to Fig. il

Referring now to Fig. 4, a three-wire dis- `tribution system isillustrated in which main and auxiliary transformers 1a and 2l areconnected. in parallel with each other, the

connections of the main and auxiliary transformers on the primary sideofthe system being similar to those illustrated. in Fig.. 2. Thesecondary winding of the main trans- ,former is divided at its middlepoint into two equal portions 42, 43 and the adjacent ends of theportions 42, 43 are connected to thev two fixed terminals 12 and 13 ofthe switch 14, the neutral Wire 44 of the distributin@r circuit beingconnected to the movswitch. The operation ofv the apparatus is asfollows: When the switch 14 is open, the circuit of the main transformeris broken and the ortion 42a and 43 of the ransformer winding are alsodisconnected om the' neutral wire 44 of the system, whereas, when theswitch is closed, the two portions 42a and 43 of the main transformerwindingare connected in series and the neutral wire 44 is joined to themiddle point thereof. The remainder of the connections of the system ofFig. 4 are similar to those already described and need not be moreparticularly referred to.

lt will be understood that any one of the systems which I have shownvand described may ybe further modified by utilizing any other knownmeans in lieu of that specifically set forth for modi ing the action ofthe electro-magnet 29 o the relay switch 26 or protecting its windingfrom injury by the heating action of excessive currents.

I claim as my invention:

In a system of alternating currentelectrical distribution, thecombination with a main and an auxiliary transformer, of means forautomatically adgusting the transformer connections in accordance withthe load, an electro-magnetically operated relay switch for controllingsaid adjusting means, and means for reducing the current supplied to theoperating magnet of the relay switch.

2. In a system of alternating current electrical distribution, thecombination with a main and an auxiliary transformer, mechanicallyconnected switches for adjustin the circuit connections of the primaryan secondary transformer windings, an electromagnetically operated relayswitch for con` trolling the operation of said mechanically connectedswitches, and means for reducing the current supplied to the operatingmagnet of the relay switc In a system of alternating current electricaldistribution, the combination of main and auxiliary transformers, ofinterconnected switchesfor adjusting the circuit connections of theprimary and secondary windings of said transformers, means tendin toclose said interconnected switches and a use in the secondary circuit ofone of said trans formers which serves to prevent said switchclosingmeans from operating until ruptured by an excessive current.

In a system of alternating current electrical distribution, thecombination with a inain and an auxiliary transformer, of mechanicallyconnected and electro-magnetically operated switches for adjusting theprimary and secondary circuits of said the actuating coil transformers,a relay switch for controlling the supply of current to the operatincoils of said mechanically connected switc es, a mechanical meanstending to close said connected switches, a latch for retaining saidclosing means in inoperative position, and a fuse in the secondarycircuit of one of said transformers for releasing said latch whentraversed by an excessive current.

5. In a system of alternating current-electrical distribution, thecombination with a main and an auxiliary transformer, of mechanicallyconnected main switches for adjusting the primary and secondary circuitconnections of said transformers, actuating coils for said mainswitches, an electro-inagnetically operated relay switch for controllingthe circuits of the actuating coils of said main switches, a seriestransformer the main circuit for supplying current to of said relayswitch, and connections to one of the main switches for short-circuitinga portion of the primary winding of said series transformer.

6. In a system of alternating current electrical distribution, thecombination 'with a main and an auxiliary transformer, of means forautomatically adjusting the circuit connections of said transformer inaccordance with the load, an elcctrornagnetically operated relay switchfor controlling said adjusting means, and means for varying the ampereturns of the operating magnet of said relay switch.

In testimony' whereof, I have hereunto subscribed my name this 23rd dayof June, 1909.

JOHN SEDGWICK PECK.

